Light-emitting diode and method for manufacturing the same

ABSTRACT

Disclosed is a light-emitting diode which includes a light-emitting epitaxial layered unit, an insulation layer, a transparent conductive layer, a protective layer, a first electrode, and a second electrode. The light-emitting epitaxial layered unit includes a first semiconductor layer, a second semiconductor layer, and a light-emitting layer sandwiched between the first and second semiconductor layers, and has a first electrode region which includes a pad area and an extension area. The insulation layer is disposed on the first semiconductor layer and at the extension area of the first electrode region. Also disclosed is a method for manufacturing the light-emitting diode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a bypass continuation-in-part application ofInternational Application No. PCT/CN2018/073362 filed on Jan. 19, 2018.The entire content of the international patent application isincorporated herein by reference.

FIELD

The disclosure relates to a light-emitting diode and a method formanufacturing the light-emitting diode.

BACKGROUND

Light emitting diodes (LEDs) have advantages properties, such as longlifespan, small size, high shock resistance, low heat generation, lowpower consumption, and etc., and thus are widely used as indicators orlight sources of home appliances and various instruments.

A conventional method for manufacturing a gallium nitride LED chipgenerally includes four steps, i.e., mesa etching, forming a transparentconductive layer (for example, an indium tin oxide layer), formingelectrodes, and forming a protective layer. The LED chip thusmanufactured is illustrated in FIG. 1.

As shown in FIG. 1, the LED chip generally includes a substrate 101, ann-type layer 111, a light-emitting layer 112, a p-type layer 113, atransparent conductive layer 120, a p-electrode 141, an n-electrode 142,and a protective layer 130. The p-electrode 141 includes a pad 143 andan extension strip 144.

In a conventional gallium nitride LED, p-GaN has a relatively lowcarrier mobility, such that current crowding effect may occur at thebottom of a pad-pad.

Therefore, referring to FIG. 2, a current blocking layer 150 is usuallyadded below the p-type electrode 141 to suppress over-injection ofcurrent and to increase current spreading of the transparent conductivelayer 120. A conventional method for manufacturing the LED chip as shownin FIG. 2 generally includes five steps, i.e., mesa etching, forming acurrent blocking layer, forming a current spreading layer (for example,an indium tin oxide layer), forming electrodes, and forming a protectivelayer.

SUMMARY

An object of the disclosure is to provide a light-emitting diode and amanufacturing method thereof, in which a protective layer, a transparentconductive layer, and an insulation layer are formed below an extensionportion of an electrode, so as to effectively enhance the light-emittingefficiency and the reliability of the light-emitting diode.

According to a first aspect of the disclosure, there is provided a lightemitting diode which includes a light-emitting epitaxial layered unit,an insulation layer, a transparent conductive layer, a protective layer,a first electrode, and a second electrode.

The light-emitting epitaxial layered unit includes a first semiconductorlayer, a second semiconductor layer, and a light-emitting layersandwiched between the first and second semiconductor layers, and has atop surface including a first electrode region. The first electroderegion includes a pad area and an extension area.

The insulation layer is disposed on the first semiconductor layer and atthe extension area of the first electrode region.

The transparent conductive layer is disposed on the first semiconductorlayer and covers the insulation layer.

The protective layer is disposed on the transparent conductive layer,and has a plurality of first holes formed above and along the extensionarea of the first electrode region to permit the transparent conductivelayer to be exposed.

The first electrode is disposed on the protective layer, and includes apad portion and an extension portion. The extension portion fills thefirst holes so as to electrically connect the transparent conductivelayer.

The second electrode is electrically connected to the secondsemiconductor layer and is spaced apart from the first electrode.

According to a second aspect of the disclosure, there is provided alight emitting diode which includes a light-emitting epitaxial layeredunit, an insulation layer, a transparent conductive layer, a protectivelayer, a first electrode, and a second electrode.

The light-emitting epitaxial layered unit includes a first semiconductorlayer, a second semiconductor layer, and a light-emitting layersandwiched between the first and second semiconductor layers, and has atop surface including a first electrode region and a second electroderegion. The second electrode region includes a pad area and an extensionarea. The light-emitting epitaxial layered unit has a plurality of vias.Each of the vias extends downwardly from the extension area of thesecond electrode region through the first semiconductor layer and thelight-emitting layer to terminate at a bottom surface in the secondsemiconductor layer so as to permit the second semiconductor layer to beexposed.

The insulation layer is disposed on the pad area and the extension areaof the second electrode region.

The transparent conductive layer is disposed on the first semiconductorlayer, and has a plurality of holes which are in positions correspondingto those of the vias, respectively.

The protective layer is disposed on the transparent conductive layer,and extends downwardly along an inner peripheral surface of each of thevias to terminate at the bottom surface of each of the vias to permitthe second semiconductor layer to be exposed.

The first electrode is disposed on the protective layer and at the firstelectrode region, and is electrically connected to the transparentconductive layer.

The second electrode is disposed on the protective layer and at thesecond electrode region, and fills the vias so as to electricallyconnect the second semiconductor layer.

According to a third aspect of the disclosure, there is provided amethod for manufacturing a light-emitting diode, which includes thesteps of:

a) providing a light-emitting epitaxial layered unit which includes afirst semiconductor layer, a second semiconductor layer, and alight-emitting layer sandwiched between the first and secondsemiconductor layers, the light-emitting epitaxial layered unit having atop surface including a first electrode region which includes a pad areaand an extension area;

b) forming an insulation layer on the extension area of the firstelectrode region of the top surface of the light-emitting epitaxiallayered unit;

c) forming a transparent conductive layer on the insulation layer andthe top surface of the light-emitting epitaxial layered unit;

d) forming a protective layer on the transparent conductive layer, theprotective layer being formed with a plurality of first holes above andalong the extension area of the first electrode region to permit thetransparent conductive layer to be exposed; and

e) forming a first electrode on the protective layer, the firstelectrode filling the first holes so as to electrically connect thetransparent conductive layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the disclosure will become apparent inthe following detailed description of the embodiments with reference tothe accompanying drawings, of which:

FIG. 1 is a schematic side view of a conventional light-emitting diode;

FIG. 2 is a schematic side view of another conventional light-emittingdiode;

FIG. 3 is a schematic top view of a first embodiment of a light-emittingdiode according to the disclosure;

FIG. 4 is a schematic side view taken along line A-A of FIG. 3;

FIG. 5 is a schematic side view taken along line B-B of FIG. 3;

FIG. 6 is a diagram comparing reflectivity of the light-emitting diodeof the first embodiment shown in FIG. 3 and those of the conventionallight-emitting diodes shown in FIGS. 1 and 2 (referred to as ComparativeExamples 1 and 2, respectively in the figure);

FIG. 7 is a partially enlarged schematic view of FIG. 4;

FIG. 8 is a schematic view illustrating photomasks for manufacturing thefirst embodiment shown in FIG. 3;

FIG. 9 is a schematic top view of a second embodiment of thelight-emitting diode according to the disclosure;

FIG. 10 is a schematic side view taken along line A-A of FIG. 9;

FIG. 11 is a schematic top view of a third embodiment of thelight-emitting diode according to the disclosure;

FIG. 12 is a schematic side view taken along line A-A of FIG. 11;

FIG. 13 is a partially enlarged schematic view of FIG. 12;

FIG. 14 is a schematic top view of a fourth embodiment of thelight-emitting diode according to the disclosure;

FIG. 15 is a schematic side view taken along line A-A of FIG. 14;

FIG. 16 is a partially enlarged schematic view of FIG. 15;

FIG. 17 is a schematic top view of a fifth embodiment of thelight-emitting diode according to the disclosure;

FIG. 18 is a schematic side view taken along line A-A of FIG. 17;

FIG. 19 is a schematic top view of a sixth embodiment of thelight-emitting diode according to the disclosure;

FIG. 20 is a schematic top view of a seventh embodiment of thelight-emitting diode according to the disclosure;

FIG. 21 is a schematic side view taken along line A-A of FIG. 20;

FIG. 22 is a partially enlarged schematic view of FIG. 21;

FIG. 23 is a schematic view illustrating photomasks for manufacturingthe seventh embodiment shown in FIG. 20;

FIG. 24 is a schematic side view of an eighth embodiment of thelight-emitting diode according to the disclosure;

FIG. 25 is a partially enlarged schematic view of FIG. 24;

FIG. 26 is a schematic side view of a ninth embodiment of thelight-emitting diode according to the disclosure;

FIG. 27 is a partially enlarged schematic view of FIG. 26;

FIG. 28 is a schematic top view of a tenth embodiment of thelight-emitting diode according to the disclosure;

FIG. 29 is a schematic side view taken along line A-A of FIG. 28;

FIG. 30 is a schematic view illustrating photomasks for manufacturingthe tenth embodiment shown in FIG. 28;

FIG. 31 is a schematic top view of an eleventh embodiment of thelight-emitting diode according to the disclosure;

FIG. 32 is a schematic side view of a twelfth embodiment of thelight-emitting diode according to the disclosure;

FIG. 33 is a schematic view illustrating a photomask for manufacturingan insulation layer in the twelfth embodiment shown in FIG. 32;

FIG. 34 is a schematic top view of a thirteenth embodiment of thelight-emitting diode according to the disclosure;

FIG. 35 is a schematic side view taken along line A-A of FIG. 34;

FIG. 36 is a partially enlarged schematic view of FIG. 35; and

FIG. 37 is a diagram comparing the reflectivity of the light-emittingdiode of the thirteenth embodiment shown in FIG. 34 and those of theconventional light-emitting diodes shown in FIGS. 1 and 2 (referred toas Comparative Examples 1 and 2, respectively in the figure).

DETAILED DESCRIPTION

Before the disclosure is described in greater detail, it should be notedthat where considered appropriate, reference numerals or terminalportions of reference numerals have been repeated among the figures toindicate corresponding or analogous elements, which may optionally havesimilar characteristics.

A light emitting diode according to a first aspect of the disclosureincludes a light-emitting epitaxial layered unit, an insulation layer, atransparent conductive layer, a protective layer, a first electrode, anda second electrode.

The light-emitting epitaxial layered unit includes a first semiconductorlayer, a second semiconductor layer, and a light-emitting layersandwiched between the first and second semiconductor layers, and has atop surface including a first electrode region. The first electroderegion includes a pad area and an extension area.

The insulation layer is disposed on the first semiconductor layer and atthe extension area of the first electrode region.

The transparent conductive layer is disposed on the first semiconductorlayer and covers the insulation layer.

The protective layer is disposed on the transparent conductive layer,and has a plurality of first holes formed above and along the extensionarea of the first electrode region to permit the transparent conductivelayer to be exposed.

The first electrode is disposed on the protective layer, and includes apad portion and an extension portion. The extension portion fills thefirst holes so as to electrically connect the transparent conductivelayer.

The second electrode is electrically connected to the secondsemiconductor layer and is spaced apart from the first electrode.

Each of the insulation layer and the protective layer has a thicknesswhich is determined according to an equation of:

d=(2k+1)Λ/4n,

wherein

d is a thickness of each of the insulation layer and the protectivelayer,

k is a natural number of at least 0,

Λ is a wavelength of light emitted from the light-emitting layer, and

n is a refractive index of each of the insulation layer and theprotective layer.

In certain embodiments, a total thickness of the insulation layer andthe protective layer is at least 300 nm.

In certain embodiments, the insulation layer includes a plurality ofinsulation blocks spaced apart from one another.

In certain embodiments, the insulation blocks of the insulation layerare in positions corresponding to those of the first holes of theprotective layer, respectively. Each of the insulation blocks of theinsulation layer has a cross-sectional area smaller than a size of acorresponding one of the first holes of the protective layer.

In certain embodiments, the transparent conductive layer covers theinsulation blocks of the insulation layer, and the transparentconductive layer and the protective layer define therebetween aplurality of clearances which are in positions corresponding to those ofthe first holes, respectively, to permit the first electrode to befilled.

In certain embodiments, each of the insulation blocks of the insulationlayer is disposed below a corresponding one of the first holes of theprotective layer, and has a cross-sectional area larger than a size of acorresponding one of the first holes of the protective layer.

In certain embodiments, a proximate one of the insulation blocksrelative to the pad area of the first electrode region have across-sectional area larger than that of a distal one of the insulationblocks relative to the pad area of the first electrode region.

In certain embodiments, proximate ones of the insulation blocks relativeto the pad area of the first electrode region are arranged more denselythan distal ones of the insulation blocks relative to the pad area ofthe first electrode region.

In certain embodiments, a part of the pad portion of the first electrodeis in direct contact with a portion of the first semiconductor layer atthe pad area of the first electrode region.

In certain embodiments, the pad area of the first electrode regionincludes a central portion, and a part of the pad portion of the firstelectrode is in direct contact with a portion of the first semiconductorlayer at the central portion of the pad area of the first electroderegion.

In certain embodiments, the insulation layer is further disposed at thepad area of the first electrode region.

In certain embodiments, the protective layer further has a second holedisposed above the first semiconductor layer at the pad area of thefirst electrode region.

In certain embodiments, the second hole has an annular geometry.

In certain embodiments, the transparent conductive layer has a thirdhole disposed above the pad area of the first electrode region, and thefirst electrode fills the second hole of the protective layer and thethird hole of the transparent conductive layer so as to permit the firstelectrode to be in direct contact with a portion of the firstsemiconductor layer at the pad area of the first electrode region.

In certain embodiments, the second hole includes at least onehole-protruding portion that protrudes radially and outwardly.

In certain embodiments, the insulation layer is further disposed on thefirst semiconductor layer at the pad area of the first electrode region.The insulation layer at the pad area of the first electrode regionincludes a plurality of insulation blocks which are arranged to surrounda center of the pad area of the first electrode region and which areangularly spaced apart from one another.

In certain embodiments, two adjacent ones of the insulation blocks atthe pad area of the first electrode region define therebetween aclearance, and the first electrode further includes an interconnectingportion which interconnect the pad portion and the extension portion andwhich is disposed above a corresponding one of the clearances.

In certain embodiments, the protective layer further has a second holedisposed above the first semiconductor layer at the pad area of thefirst electrode region. The second hole includes at least onehole-protruding portion that protrudes radially and outwardly.

In certain embodiments, the second hole includes a plurality of thehole-protruding portions respectively aligned with the insulation blocksat the pad area of the first electrode region.

In certain embodiments, the second hole includes a plurality of thehole-protruding portions which are staggered from the insulation blocksdisposed at the pad area of the first electrode region.

In certain embodiments, the top surface of the light-emittingepitaxiallayered unit further includes a second electrode region on which thesecond electrode is disposed. The second electrode region includes amesa portion at which the second semiconductor layer is exposed. Theprotective layer covers the mesa portion, and further has a fourth holeto permit a part of the second semiconductor layer to expose.

In certain embodiments, the insulation layer is further disposed on thepad area of the second electrode region and is sandwiched between theprotective layer and the second semiconductor layer.

In certain embodiments, the top surface of the light-emitting epitaxiallayered unit further includes a second electrode region configured as amesa-shaped surface on which the second electrode is disposed. Thesecond electrode includes an extension portion which is disposed on theprotective layer and which extends downwardly to penetrate through thefirst semiconductor layer and the light-emitting layer so as to form anohmic contact with the second semiconductor layer.

In certain embodiments, the insulation layer, the transparent conductivelayer, and the protective layer are laminated sequentially on the firstsemiconductor layer, and are disposed between the extension portion ofthe second electrode and the first semiconductor layer.

In certain embodiments, the transparent conductive layer and theprotective layer are laminated sequentially on the first semiconductorlayer, and are disposed between the extension portion of the secondelectrode and the first semiconductor layer.

In certain embodiments, the first electrode has an undulating topsurface.

In certain embodiments, the pad portion of the first electrode has astepped top surface.

In certain embodiments, the pad portion of the first electrode has arecessed top surface.

In certain embodiments, the recessed top surface of the pad portion ofthe first electrode has at least two recesses.

In certain embodiments, the recessed top surface of the pad portion ofthe first electrode has a central recess and a surrounding recesssurrounding the central recess.

In certain embodiments, the central recess is deeper than thesurrounding recess.

A light emitting diode according to a second aspect of the disclosureincludes a light-emitting epitaxial layered unit, an insulation layer, atransparent conductive layer, a protective layer, a first electrode, anda second electrode.

The light-emitting epitaxial layered unit includes a first semiconductorlayer, a second semiconductor layer, and a light-emitting layersandwiched between the first and second semiconductor layers, and has atop surface including a first electrode region and a second electroderegion. The second electrode region includes a pad area and an extensionarea. The light-emitting epitaxial layered unit has a plurality of vias.Each of the vias extends downwardly from the extension area of thesecond electrode region through the first semiconductor layer and thelight-emitting layer to terminate at a bottom surface in the secondsemiconductor layer so as to permit the second semiconductor layer to beexposed.

The insulation layer is disposed on the pad area and the extension areaof the second electrode region.

The transparent conductive layer is disposed on the first semiconductorlayer, and has a plurality of holes which are in positions correspondingto those of the vias, respectively.

The protective layer is disposed on the transparent conductive layer,and extends downwardly along an inner peripheral surface of each of thevias to terminate at the bottom surface of each of the vias to permitthe second semiconductor layer to be exposed.

The first electrode is disposed on the protective layer and at the firstelectrode region, and is electrically connected to the transparentconductive layer.

The second electrode is disposed on the protective layer and at thesecond electrode region, and fills the vias so as to electricallyconnect the second semiconductor layer.

In certain embodiments, the insulation layer is further disposed on theextension area of the second electrode region, and the transparentconductive layer covers the insulation layer on the extension area ofthe second electrode region.

In certain embodiments, the first electrode includes a pad portion andan extension portion. The insulation layer, the transparent conductivelayer, and the protective layer are laminated sequentially on the firstsemiconductor layer, and are disposed between the extension portion ofthe first electrode and the first semiconductor layer.

In certain embodiments, the pad portion of the first electrode is indirect contact with the first semiconductor layer.

In certain embodiments, the pad portion of the first electrode has astepped top surface.

In certain embodiments, the extension portion of the first electrode hasa stepped top surface.

In certain embodiments, the second electrode includes a pad portion andan extension portion, and the protective layer is disposed between thepad portion of the second electrode and the insulation layer.

A method for manufacturing a light-emitting diode according to a thirdaspect of the disclosure includes the steps of:

a) providing a light-emitting epitaxial layered unit which includes afirst semiconductor layer, a second semiconductor layer, and alight-emitting layer sandwiched between the first and secondsemiconductor layers, the light-emitting epitaxial layered unit having atop surface including a first electrode region which includes a pad areaand an extension area;

b) forming an insulation layer on the extension area of the firstelectrode region of the top surface of the light-emitting epitaxiallayered unit;

c) forming a transparent conductive layer on the insulation layer andthe top surface of the light-emitting epitaxial layered unit;

d) forming a protective layer on the transparent conductive layer, theprotective layer being formed with a plurality of first holes above andalong the extension area of the first electrode region to permit thetransparent conductive layer to be exposed; and

e) forming a first electrode on the protective layer, the firstelectrode filling the first holes so as to electrically connect thetransparent conductive layer.

In certain embodiments, in step a), the light-emitting epitaxial layeredunit has a plurality of vias, and the top surface of the light-emittingepitaxial layered unit further includes a second electrode regionconfigured as a mesa-shaped surface from which the second semiconductorlayer is exposed partially. In step d), the protective layer covers themesa-shaped surface and is formed with a plurality of openings which arealigned with the vias, respectively, so as to permit the secondsemiconductor layer to be exposed. In step e), a second electrode isfurther formed on the protective layer, and fills the vias of theprotective layer so as to be in contact with the second semiconductorlayer.

In certain embodiments, in step e), the first electrode region islocated on the first semiconductor layer, and the first electrode isformed directly on the pad area of the first electrode region so as tobe in direct contact with the first semiconductor layer.

Referring to FIGS. 3 to 5, a first embodiment of a light-emitting diodeaccording to the disclosure includes includes a substrate 201, an n-typelayer 211, a light-emitting layer 212, a p-type layer 213, an insulationlayer 221, a transparent conductive layer 230, a protective layer 222, afirst electrode 241, and a second electrode 242. The first electrode 241includes a pad portion 243 and an extension portion 244, and the secondelectrode 242 also includes a pad portion 245 and an extension portion246.

The substrate may be made of sapphire, aluminum nitride, galliumnitride, silicon, silicon carbide, or the like, and may have a flatsurface structure or a patterned surface structure. The n-type layer 211is disposed on the substrate 201. The light-emitting layer 212 isdisposed on the n-type layer 211. The p-type layer 213 is disposed onthe light-emitting layer 212.

The n-type layer 211, the light-emitting layer 212, and p-type layer 213cooperate with one another to form a light-emitting epitaxial layeredunit. The light-emittingepitaxial layered unit has a top surface whichincludes a first electrode region and a second electrode region. Each ofthe first and second electrode regions includes a pad area and anextension area. The second electrode region is configured as amesa-shaped surface 210 from which the n-type layer 211 is exposedpartially, and has an upper surface portion and a lower surface portion.

The light-emitting epitaxial layered unit has a plurality of vias 254.Each of the vias 254 extends downwardly from the extension area of thesecond electrode region through the p-type layer 213 and thelight-emitting layer 212 to terminate at a bottom surface in the n-typelayer 211 so as to permit the n-type 211 to be exposed.

The insulation layer 221 is disposed below the first electrode 241.Specifically, the insulation layer 221 is disposed on the p-type layer213 and at the pad area and the extension area of the first electroderegion. The insulation layer 221 disposed at the extension area of thefirst electrode region includes a plurality of insulation blocks spacedapart from one another. In addition, the insulation layer 221 is furtherdisposed on the pad area of the second electrode region. The insulationlayer 221 disposed on the pad area of the second electrode region issandwiched between the protective layer 222 and the n-type layer 211.

The transparent conductive layer 230 is disposed on the p-type layer 213and covers the insulation layer 221.

The protective layer 222 is disposed on the transparent conductive layer230, and has a plurality of first holes 251 formed above and along theextension area of the first electrode region to permit the transparentconductive layer 230 to be exposed. In the first embodiment, theprotective layer 222 substantially covers the top surface of thelight-emitting epitaxial layered unit. The protective layer 222 furtherhas a second hole 252 disposed above the p-type layer 213 at the padarea of the first electrode region. In addition, the protective layer222 covers the mesa-shaped surface 210 and further has a fourth hole 255on the lower surface portion of the mesa-shaped surface 210.

The first electrode 241 is disposed on the protective layer 222. Theextension portion 244 of the first electrode 241 fills the first holes251 so as to electrically connect the transparent conductive layer 230.In addition, the pad portion 243 of the first electrode 241 is incontact with the transparent conductive layer 230 through the secondhole 252.

The second electrode 242 is disposed on the mesa-shaped surface, iselectrically connected to the n-type 211, and is spaced apart from thefirst electrode 241. The pad portion 245 of the second electrode 242 isdisposed on the lower surface portion of the mesa-shaped surface 210,and is in contact with the n-type layer 211 through the fourth hole 255.The extension portion 246 of the second electrode 242 is disposed on theprotective layer 222 and extends downwardly to be in contact with then-type layer 211 through the vias 254.

Referring specifically to FIG. 4, the insulation layer 221, thetransparent conductive layer 230, and the protective layer 222 arelaminated sequentially on the p-type layer 213, and are disposed betweenthe extension portion 244 of the first electrode 241 and the p-typelayer 213.

The material for making each of the insulation layer 221 and theprotective layer 222 may be an insulation material having a lowrefractive index (for example, at most 1.5). The materials for makingthe insulation layer 221 and the protective layer 222 may be the same ordifferent.

The first holes 251 of the protective layer 222 are staggered from theinsulation blocks of the insulation layer 221. The extension portion 244of the first electrode 241 has a stepped top surface including a firstsurface 244A, a second surface 244B, and a third surface 244C.

The insulation layer 221 below the extension portion 244 of the firstelectrode 241 may be used as a current blocking layer so as to inhibitthe over-injection of current below the extension portion 244 of thefirst electrode 241 and to increase the length and uniformity of thecurrent injection.

The protective layer 222 is formed on the transparent conducting layer230, followed by formation of the first electrode 241. Therefore, theprobability of the active metal in the first electrode 241 beingoxidized during formation of the protective layer 222 may be reduced.

The design of the insulation layer 221 and the protective layer 222 canreduce the metal light-blocking area of the first electrode 241 and/orthe second electrode 242 and the pad area(s) of the first electroderegion and/or the second electrode region by utilizing the refractioneffect, and thus improve the light extraction efficiency of thelight-emitting diode. In addition, The insulation layer 221, thetransparent conductive layer 230, the protective layer 222, and theelectrode extension portion 244 of the first electrode 241 and/or thethe electrode extension portion 246 of the second electrode 242 aredesigned to act as an omni-directional reflector, so that the reflectioncapability of the first and second electrodes 241, 242 and the extensionarea thereof may be improved and the light absorption effect may bereduced.

Referring to FIG. 6, the overall reflection efficiency of the firstembodiment of the light-emitting diode according to the disclosure issuperior to those of the conventional light-emitting diodes shown inFIGS. 1 and 2.

The protective layer 222 may be made of SiO₂, SiN₄, Al₂O₃, TiO₂, or thelike, to protect the light-emitting diode from being damaged.Alternatively, the protective layer 222 may be used together with theinsulation layer 221 as a complex current blocking layer for inhibitingthe over-injection of current below the the first electrode 241 and forincreasing the current spreading of the transparent conductive layer230.

The protective layer 222 has a thickness which is determined accordingto an equation of:

d=(2k+1)Λ/4n,

wherein

d is a thickness of the protective layer 222,

k is a natural number of at least 0 (for example, 1 or 2),

Λ is a wavelength of light emitted from the light-emitting layer 212,and

n is a refractive index of the protective layer 222.

The suitable thickness of the protective layer 222 ranges from 150 nm to500 nm. When the thickness of the the protective layer 222 is too small,the current blocking effect and the protection effect are insufficient.When the protective layer 222 is too large, the light emitted from thelight-emitting layer 212 may be excessively absorbed by the protectivelayer 222, such that the light-emitting efficiency of the light-emittingdiode is reduced.

Referring to FIG. 7, the transparent conductive layer 230 has a thirdhole 253, which is disposed above the pad area of the first electroderegion and which is in a position corresponding to that of the padportion 243 of the first electrode 241. An insulation portion 221A ofthe insulation layer 221 is formed in the third hole 253. The insulationportion 221A has a diameter (D3) smaller than a diameter (D4) of thethird hole 253. The second hole 252 of the protective layer 222 is in aposition corresponding to that of the pad portion 243 of the firstelectrode 241. The second hole 252 is configured as an annular geometrywhich has an inner diameter (D1) and an outer diameter (D2). The innerdiameter (D1) and the outer diameter (D2) of the second hole 252, thediameter (D3) of the insulation portion 221A, and the diameter (D4) ofthe third hole 253 have a relationship of D2>D4>D1>D3.

The pad portion 243 of the first electrode 241 fills the second hole 252of the protective layer 222 and the third hole 253 of the transparentconductive layer 230 so as to permit the pad portion 243 of the firstelectrode 241 to be in direct contact with a portion of the p-type layer213 at the pad area of the first electrode region. Specifically, the padportion 243 of the first electrode 241 is in contact with the p-typelayer 213, the transparent conductive layer 230, and the protectivelayer 222.

The pad portion 243 of the first electrode 241 has a stepped topsurface. The protective layer 222 below the pad portion 243 of the firstelectrode 241 is used as a current blocking layer. When the currentflows through the first electrode 241, most of the current flows fromthe extension portion 244 of the first electrode 241 through the firstholes 251 of the protective layer 222 into the transparent conductivelayer 230, and the remainder of the current flows from the pad portion243 of the first electrode 241 into a transparent conductive portion230A of the transparent conductive layer 230, followed by spreading inthe transparent conductive layer 230 so as to inject into thelight-emitting epitaxial layered unit.

In a variation of the first embodiment, the insulation portion 221A ofthe insulation layer 221 is not formed in the third hole 253 of thetransparent conductive layer 230, and the protective layer 222 fills thethird hole 253 directly.

In another variation of the first embodiment, the insulation portion221A of the insulation layer 221 is not formed in the third hole 253 ofthe transparent conductive layer 230, the second hole 252 of theprotective layer 222 is configured as a circular opening, the insulationlayer 221 and the protective layer 230 is not formed below the padportion 243 of the first electrode 241, and the protective layer 222 isin direct contact with the p-type layer 213 to increase the contact areabetween the pad portion 243 of the first electrode 241 and the p-typelayer 213, such that the adhesion between the pad portion 243 of thefirst electrode 241 and the p-type layer 213 may be enhanced so as toreduce the stripping risk of the first electrode 241 during wirebonding.

Referring specifically to FIG. 3, the second hole 252 of the theprotective layer 222 includes at least one hole-protruding portion 252 cthat protrudes radially and outwardly. The number of the hole-protrudingportion 252 c may range from 2 to 20. The pad portion 243 of the firstelectrode 241 is in contact with the transparent conductive layer 230through the at least one hole-protruding portion 252 c, so as toincrease the contact area between the pad portion 243 of the firstelectrode 241 and the transparent conductive layer 230. Therefore,spreading of the current may be enhanced, such that current congestioneffect on the pad portion 243 and the extension portion 244 of the firstelectrode 241 may be alleviated, thereby reducing the risks of metalprecipitation and electrode burning.

In the first embodiment, the protective layer 222 of the light emittingdiode protects the light emitting diode from being damaged, and can bedirectly used as a current blocking layer for inhibiting theover-injection of the current below the first and second electrodes 241,242 and for increasing the current spreading of the transparentconductive layer 230. The first electrode 241 is in direct contact withthe p-type layer 213 at the pad area of the first electrode region, sothat the adhesion between the first electrode 241 and the light-emittingepitaxial layered unit is increased effectively, and the risk of thefirst electrode 241 being stripped during wire bonding may be reduced.The pad portion 243 of the first electrode 241 is designed as amulti-stepped configuration, such that the impact force of a weldingwire can be buffered effectively, so as to reduce the impact and damageto the pad portion 243 of the first electrode 241 during the wirebonding. The extension portion 244 of the first electrode 241 isdisposed on the protective layer 222, and extends through the firstholes 251 of the protective layer 222 to be in contact with thetransparent conductive layer 230, such that the extension portion 244 ofthe first electrode 241 is formed with an undulating and steppedconfiguration. Therefore, the light-emitting angle at the extensionportion 244 of the first electrode 241 may be increased, and the lightextraction efficiency may be enhanced.

In addition, the undulating and stepped configuration of the extensionportion 244 of the first electrode 241 may reduce the contact areabetween the first electrode 241 and other objects, such that the damageto the extension portion 244 of the first electrode 241 during thesubsequent procedures, such as inversion, transportation, and transfer,may be reduced effectively, and the dirt of the extension portion 244 ofthe first electrode 241 may be decreased as well.

Referring to FIG. 8, a method for manufacturing the first embodiment ofthe light-emitting diode according to the disclosure includes the stepsof a) providing the light-emitting epitaxial layered unit, b) formingthe insulation layer 221, c) forming the transparent conductive layer230, d) forming the protective layer 222, and e) forming the first andsecond electrodes 241, 242.

In step a), the light-emitting epitaxial layered unit is provided, whichincludes the substrate 201, the n-type layer 211, the light-emittinglayer 212, and the p-type layer 213. The light-emitting layer 212 issandwiched between the n-type layer 211 and the p-type layer 213. Thelight-emitting epitaxial layered unit is subjected to mesa etching toform a plurality of the vias 254 and a mesa-shaped surface 210. Thelight-emitting epitaxial layered unit has the top surface including thefirst electrode region and the second electrode region. The secondelectrode region has the mesa-shaped surface 210, from which the n-typelayer 211 is exposed partially. Each of the first and second electroderegions includes the pad area and the extension area.

In step b), the insulation layer 221 is formed on the pad area and theextension area of the first electrode region and the pad area of thesecond electrode region of the top surface of the light-emittingepitaxial layered unit.

In step c), the transparent conductive layer 230 is formed on theinsulation layer 221 and the top surface of the light-emitting epitaxiallayered unit. The transparent conductive layer 230 is subjected toetching to remove a portion of the transparent conductive layer 230 atthe pad area of the second electrode region and to form the third hole253 at the pad area of the first electrode region and a plurality ofopenings 254″ which are aligned with the vias 254, respectively.

In step d), the protective layer 222 is formed on the transparentconductive layer 230 and covers the mesa-shaped surface 210. Theprotective layer 222 is formed with a plurality of the first holes 251above and along the extension area of the first electrode region topermit the transparent conductive layer 230 to be exposed. Theprotective layer 222 is formed with a plurality of openings 254′ whichare aligned with the vias 254, respectively so as to permit the secondsemiconductor layer 211 to be exposed. In addition, the protective layer222 is further formed with the second hole 252 at the pad area of thefirst electrode region and the fourth hole 255 on the lower surfaceportion of the mesa-shaped surface 210.

In step e), the first electrode 241 and the second electrode 242 areformed on the protective layer 222. The first electrode 241 fills thefirst holes 251 of the protective layer 222 so as to electricallyconnect the transparent conductive layer 230. Specifically, the padportion 243 of the first electrode 231 is in contact with the p-typelayer 213, the transparent conductive layer 230, and the protectivelayer 222. The second electrode 242 fills the vias 254 so as to be indirect contact with the n-type layer 211.

In should be noted that there is no limitation to the geometry and thesize of the second hole 252 of the protective layer 222. For example, incertain embodiments, the second hole 252 of the protective layer 222 isconfigured as a circular opening (i.e., the protective layer 222 belowthe pad portion 243 of the first electrode 241 is omitted), and the padportion 243 of the first electrode 241 is formed directly on the padarea of the first electrode region so as to be in direct contact withthe p-type layer 213 at a central portion of the pad area of the firstelectrode region. In certain embodiments, the second hole 252 of theprotective layer 222 is composed of a plurality of protruding openingssurrounding the periphery of the pad area of the first electrode regionto expose the transparent conductive layer 230, and does not have anopening at the pad area of the first electrode region. The pad portion243 of the first electrode 241 is formed on the protective layer 222 andis electrically connected to the transparent conductive layer 230 usingmetal leads passing through the protruding openings.

Referring to FIGS. 9 and 10, a second embodiment of the light-emittingdiode according to the disclosure is similar to the first embodimentexcept that the insulation layer 221 below the extension portion 244 ofthe first electrode 241 is configured as an insulation extension strip,so that the current injection below the first electrode 241 may becompletely avoided. In addition, the height of the extension portion 244of the first electrode 241 is raised, such that the light blocking areaof the metal of the extension portion 244 of the first electrode 241 canbe reduced effectively by the refraction effect, thereby improving thelight extraction efficiency of the light-emitting diode.

Referring to FIGS. 11 to 13, a third embodiment of the light-emittingdiode according to the disclosure is similar to the first embodimentexcept for the following differences.

In the third embodiment, the insulation blocks of the insulation layer221 are in positions corresponding to those of the first holes 251 ofthe protective layer 222, respectively. Each of the insulation blocks ofthe insulation layer 221 has a cross-sectional area smaller than a sizeof a corresponding one of the first holes 251 of the protective layer222.

Referring specifically to FIG. 13, the transparent conductive layer 230covers the insulation layer 221, and the transparent conductive layer230 and the protective layer 222 define therebetween a plurality ofclearances which are in positions corresponding to those of the firstholes 251, respectively, to permit the extension portion 244 of thefirst electrode 241 to be filled. Therefore, the adhesion between theextension portion 244 of the first electrode 241 and the protectivelayer 222 is enhanced so as to prevent the extension portion 241 of thefirst electrode 241 from stripping. In addition, the contact areabetween the extension portion 244 of the first electrode 241 and thetransparent conductive layer 230 is increased, which is beneficial tocurrent spreading, thereby alleviating the current congestion effect onthe pad portion 243 and the extension portion 244 of the first electrode241, and reducing the risk of metal precipitation and electrode burning.

Referring to FIGS. 14 to 16, a fourth embodiment of the light-emittingdiode according to the disclosure is similar to the third embodimentexcept for the following differences.

In the fourth embodiment, each of the insulation blocks of theinsulation layer 221 is disposed below a corresponding one of the firstholes 251 of the protective layer 222, and has a cross-sectional arealarger than a size of a corresponding one of the first holes 251 of theprotective layer 222.

Referring specifically to FIG. 16, the lower surface of the extensionportion 244 of the first electrode 241 is formed with a plurality ofrecesses for the protective layer 222 to extend therein. Therefore, theadhesion between the extension portion 244 of the first electrode 241and the protective layer 222 is enhanced so as to prevent the extensionportion 244 of the first electrode 241 from stripping. In addition, theextension portion 244 of the first electrode is formed with anundulating top surface which has lower surfaces 244A and higher surfaces244B. A total surface area of the higher surfaces 244B is significantlysmaller than that of the lower surfaces 244A. Therefore, the contactarea between the first electrode 241 and other objects may be reducedsignificantly, such that the damage to the extension portion 244 of thefirst electrode 241 during the subsequent procedures, such as inversion,transportation, and transfer may be reduced effectively, and the dirt ofthe extension portion 244 of the first electrode 241 may be decreased aswell.

Referring to FIGS. 17 and 18, a fifth embodiment of the light-emittingdiode according to the disclosure is similar to the third embodimentexcept for the following differences.

In the fifth embodiment, proximate ones of the insulation blocksrelative to the pad area of the first electrode region are arranged moredensely than distal ones of the insulation blocks relative to the padarea of the first electrode region, such that a superior currentspreading may be obtained.

Referring to FIG. 19, a sixth embodiment of the light-emitting diodeaccording to the disclosure is similar to the third embodiment exceptfor the following differences.

In the sixth embodiment, a proximate one of the insulation blocksrelative to the pad area of the first electrode region have across-sectional area larger than that of a distal one of the insulationblocks relative to the pad area of the first electrode region, such thata superior current spreading may be obtained.

Referring to FIGS. 20 to 22, a seventh embodiment of the light-emittingdiode according to the disclosure is similar to the first embodimentexcept for the following differences.

In the seventh embodiment, the insulation layer 221 includes an annularinsulation portion 221′, which is disposed below the pad portion 243 ofthe first electrode 241, and which has an hole 256. The hole 256 of theannular insulation portion 221′ of the insulation layer 221 is in aposition corresponding to that of the third hole 253 of the transparentconductive layer 230, and has a size not larger than that of the thirdhole 253. The second hole 252 of the protective layer 222 includes acentral hole portion 257, and a surrounding hole portion 258 whichsurrounds the central hole portion 257 and which is spaced apart fromthe central hole portion 257 by a surrounding wall 222A. The surroundinghole portion 258 permits the transparent conductive layer 230 to beexposed, such that the pad portion 243 of the first electrode 241 is incontact with the transparent conductive layer 230. The central holeportion 257 permits the p-type layer 213 to be exposed, such that thepad portion 243 of the first electrode 241 is in contact with the p-typelayer 213.

Referring specifically to FIG. 22, the third hole 253 of the transparentconductive layer 230 has a diameter (D4), the hole 256 of the annularinsulation portion 221′ has a diameter (D5), the annular insulationportion 221′ has an outer diameter (D6), and the central hole portion257 of the second hole 252 of the protective layer 222 has a diameter(D7). The diameters (D4, D5, D6, D7) have a relationship of D6>D4>D5>D7,such that a central part of the pad portion 243 of the first electrode241 is in contact with the p-type layer 213.

The pad portion 243 of the first electrode 241 has a recessed topsurface which has two recesses. Specifically, the recessed top surfaceof the pad portion 243 of the first electrode 241 has a central recess243A and a surrounding recess 243B surrounding the central recess 243A.The central recess 243A is deeper than the surrounding recess 243B,which is beneficial for subsequent wire bonding.

Referring to FIG. 23, a method for manufacturing the seventh embodimentis similar to that for manufacturing the first embodiment except for thefollowing differences.

In the method for manufacturing the seventh embodiment, a photomask forforming the insulation layer 221 (i.e., step b)) has an annular openingfor forming the hole 256 of the annular insulation portion 221′. Aphotomask for forming the protective layer 222 (i.e., step d)) has anopening for forming the central hole portion 257 of the second hole 252of the protective layer 222.

In a variation of the seventh embodiment, the central hole portion 257and the surrounding hole portion 258 of the second hole 252 of theprotective layer 222 are not spaced apart from each other by thesurrounding wall 222A so as to merge together to form a single hole,such that the pad portion 243 of the first electrode 241 is in contactwith the protective layer 222, the transparent conductive layer 230, theannular insulation portion 221′, and the p-type layer 213. The recessedtop surface of the pad portion 243 of the first electrode 241 may havemore than two recesses.

Referring to FIGS. 24 and 25, an eighth embodiment of the light-emittingdiode according to the disclosure is similar to the third embodimentexcept for the following differences.

In the eighth embodiment, the insulation layer 221 has a thickness whichis significantly greater than that of the protective layer 222 and evengreater than a total thickness of the transparent conductive layer 230and the protective layer 222.

In certain embodiments, the insulation layer 221 and the protectivelayer 222 are made of a same material, and the difference of thicknesstherebetween is determined by an equation of:

(2k)Λ/4n,

wherein

-   -   k is a natural number of at least 1,    -   Λ is a wavelength of light emitted from the light-emitting layer        212, and    -   n is a refractive index of the insulation layer 221.

In certain embodiments, the thickness of the insulation layer 221 rangesfrom 300 nm to 1000 nm, and the thickness of the protective layer 222ranges from 100 nm to 250 nm.

Referring specifically to FIG. 25, when the thickness of the insulationlayer 221 is increased, the surface area of the transparent conductivelayer 230 may be increased, so that the contact area between theextension portion 244 of the first electrode 241 and the transparentconductive layer 230 may be increased, which is beneficial to currentspreading. Therefore, the current congestion effect on the pad portion243 and the extension portion 244 of the first electrode 241 may bealleviated, and the risks of metal precipitation and electrode burningmay be reduced. In addition, a groove structure may be formed betweenadjacent two of the insulation blocks of the insulation layer 221, sothat the adhesive force provided to the extension part 244 of the firstelectrode 241 may be increased, and the risk of the first electrode 241being stripped may be reduced.

Referring to FIGS. 26 and 27, a ninth embodiment of the light-emittingdiode according to the disclosure is similar to the eighth embodimentexcept for the following differences.

In the ninth embodiment, the thickness of the protective layer 222 issignificantly greater than that of the insulation layer 221.

In certain embodiments, the insulation layer 221 and the protectivelayer 222 are made of a same material, and the difference of thicknesstherebetween is determined by an equation of:

(2k)Λ/4n,

wherein

-   -   k is a natural number of at least 1,    -   Λ is a wavelength of light emitted from the light-emitting layer        212, and    -   n is a refractive index of the protective layer 222.

In certain embodiments, the thickness of the insulation layer 221 rangesfrom 50 nm to 300 nm, and the thickness of the protective layer 222ranges from 200 nm to 2000 nm.

Referring specifically to FIG. 27, since the thickness of the insulationlayer 221 is significantly less than that of the protective layer 222,the insulation blocks of the insulation layer 221 are in positionscorresponding to those of the first holes 251 of the protective layer222, respectively, below the extension portion 244 of the firstelectrode 241, such that the protective layer 222 is formed with aplurality of recesses which are in positions corresponding to those ofthe insulation blocks of the insulation layer 221. Therefore, theextension portion 244 of the first electrode 241 may fill the recesses,such that the adhesive force provided to the extension part 244 of thefirst electrode 241 is increased and the risk of the first electrode 241being stripped is reduced.

Referring to FIGS. 28 and 29, a tenth embodiment of the light-emittingdiode according to the disclosure is similar to the first embodimentexcept for the following differences.

In the tenth embodiment, in addition to the insulation portion 221A, theinsulation layer 221 at the pad area of the first electrode regionfurther includes a plurality of insulation blocks 221B which arearranged to surround a center of the pad area of the first electroderegion and which are angularly spaced apart from one another.Specifically, the insulation blocks 221B surround the insulation portion221A, and cooperatively define an outer diameter which may be greaterthan, equal to, or less than a diameter of the pad portion 243 of thefirst electrode 241. The second hole 252 includes a plurality of thehole-protruding portions which are staggered from the insulation blocks221B disposed at the pad area of the first electrode region.

Referring to FIG. 30, a method for manufacturing the tenth embodiment issimilar to that for manufacturing the first embodiment except for thefollowing differences.

In the method for manufacturing the tenth embodiment, a photomask forforming the insulation layer 221 (i.e., step b)) further has a pluralityof surrounding holes for forming the insulation blocks 221B.

The insulation blocks 221B may increase the undulation of the topsurface of the pad portion 243 of the first electrode 241, such that thereliability of the bonding wire may be enhanced and the solder ball willnot be easily stripped or pushed off under an external force.

Referring to FIG. 31, an eleventh embodiment of the light-emitting diodeaccording to the disclosure is similar to the tenth embodiment exceptfor the following differences.

In the eleventh embodiment, two adjacent ones of the insulation blocks221B at the pad area of the first electrode region define therebetween aclearance, and the first electrode 241 further includes aninterconnecting portion 243C which interconnects the pad portion 243 andthe extension portion 244 and which is disposed above a correspondingone of the clearances, such that the pad portion 243 of the firstelectrode 241 is in a position higher than that of the interconnectingportion 243C. Therefore, the interconnecting portion 243C may be noteasily damaged by solder balls used in subsequent wire bonding, and thestability of a chip may be improved.

The protective layer 222 further has the second hole 252 disposed abovethe p-type layer 213 at the pad area of the first electrode region. Thesecond hole 252 includes a plurality of the hole-protruding portions 252c that protrudes radially and outwardly and are angularly spaced apartfrom one another. The hole-protruding portions 252 c are respectivelyaligned with the insulation blocks 221B at the pad area of the firstelectrode region.

Referring to FIGS. 32 and 33, a twelfth embodiment of the light-emittingdiode according to the disclosure is similar to the tenth embodimentexcept for the following differences.

In the twelfth embodiment, the insulation layer 221 at the pad area ofthe first electrode region is composed of a plurality of the insulationblocks 221B (i.e. without the insulation portion 221A), such that thecentral part of the pad portion 243 of the first electrode 241 is indirect contact with the p-type layer 213.

Since the central part of the pad portion 243 of the first electrode 241is in direct contact with the p-type layer 213, the adhesion between thepad portion 243 of the first electrode 241 and the light-emittingepitaxial layered unit is increased. In addition, the pad portion 243 ofthe first electrode 241 is formed with a stepped top surface 243B, whichis beneficial for subsequent wire bonding.

Referring FIGS. 34 to 36, a thirteenth embodiment of the light-emittingdiode according to the disclosure is similar to the first embodimentexcept for the following differences.

In the thirteenth embodiment, the insulation layer 221 is furtherdisposed on the extension area of the second electrode region, and thetransparent conductive layer 230 covers the insulation layer 221 on theextension area of the second electrode region.

Referring specifically to FIG. 35, the insulation layer 221, thetransparent conductive layer 230, and the protective layer 222 arelaminated sequentially on the p-type layer 213, and are disposed betweenthe extension portion 246 of the second electrode 242 and the p-typelayer 213.

Referring specifically to FIG. 36, the extension portion 246 of thesecond electrode 242 is formed on the protective layer 222, and thetransparent conductive layer 230, the insulation layer 221, and theP-type layer 213 are disposed under the protective layer 222 in suchorder. The extension portion 246 of the second electrode 242 isconductive to the n-type layer 211 through the vias 254. In addition,the protective layer 222 and the insulation layer 221 are disposed underthe pad portion 245 of the second electrode 242.

The spacing distances or the sizes of the vias 254 may be changed toalleviate current crowding effect and to improve uniformity of currentinjection, so as to enhance the stability of the light-emitting diode.

In the embodiment, the insulation layer 221 and the protective layer 222are formed below the second electrode 242. The insulation layer 221 andthe protective layer 222 are made of materials having alow-refractive-index (preferably less than 1.5) to increase thethickness thereof, such that the total reflection effect is enhanced andthe total reflectivity is increased.

Referring to FIG. 37, in the light-emitting diode of Comparative Example1, an insulation layer and a protective layer are not disposed under asecond electrode. In the light-emitting diode of Comparative Example 2,only a protective layer, which is made of SiO₂ and has a thickness of230 nm, is disposed under a second electrode. In the light-emittingdiode of Example 13, both the insulation layer 221 and the protectivelayer 222, which are made of SiO₂ and has a total thickness of 460 nm,are disposed under the second electrode 242. As shown by the graphs inFIG. 37, the overall reflectivity of the light-emitting diode of Example13 is better than those of Comparative Examples 1 and 2.

In the light-emitting diode according to the disclosure, the protectivelayer is formed on the transparent conducting layer, followed byformation of the first and second electrodes. Therefore, on one hand,the protective layer may protect the light-emitting diode from beingdamaged, and on the other hand, the protective layer and the insulationlayer may be used together as a complex current blocking layer forinhibiting over-injection of current below the first and/or secondelectrodes and for increasing current spreading of the transparentconductive layer.

The first electrode is in direct contact with the first semiconductorlayer at the pad area of the first electrode region, so that theadhesion between the first electrode and the light-emitting epitaxiallayered unit may be enhanced effectively, and the risk of the firstelectrode being stripped during wire bonding may be reduced.

The insulation layer and the protective layer are designed to reduce themetal light-blocking area of the first and/or second electrode and theexpansion area thereof by utilizing the refraction effect, and thusimproves the light extraction efficiency of the light-emitting diode.

The insulation layer, the transparent conductive layer, the protectivelayer, and the first and/or second electrode are designed to act as anomni-directional reflector, so that the reflecting capability of thefirst and/or second electrode can be improved, and the light absorptioneffect can be reduced.

The protective layer is formed on the transparent conducting layer,followed by formation of the first and second electrodes, so that theprobability of the active metal in the first and second electrodes beingoxidized during formation of the protective layer may be reduced.

The insulation layer below the extension portion of the first electrodemay inhibit the over-injection of the current below the extensionportion of the first electrode, and increase the length and uniformityof the current injection.

The insulation layer and the protective layer are disposed below theextension portion of the first electrode, so that the extension portionof the first electrode is formed with an undulating top surface.Therefore, the damage to the extension portion of the first electrode,which may occur during subsequent procedures, such as inversion,transportation, transfer, and the like, may be reduced.

The insulation layer is disposed below the extension portion of thesecond electrode, so that the transverse spreading and the uniformity ofthe current may be increased.

In the description above, for the purposes of explanation, numerousspecific details have been set forth in order to provide a thoroughunderstanding of the embodiments. It will be apparent, however, to oneskilled in the art, that one or more other embodiments may be practicedwithout some of these specific details. It should also be appreciatedthat reference throughout this specification to “one embodiment,” “anembodiment,” an embodiment with an indication of an ordinal number andso forth means that a particular feature, structure, or characteristicmay be included in the practice of the disclosure. It should be furtherappreciated that in the description, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure and aiding in theunderstanding of various inventive aspects, and that one or morefeatures or specific details from one embodiment may be practicedtogether with one or more features or specific details from anotherembodiment, where appropriate, in the practice of the disclosure.

While the disclosure has been described in connection with what areconsidered the exemplary embodiments, it is understood that thisdisclosure is not limited to the disclosed embodiments but is intendedto cover various arrangements included within the spirit and scope ofthe broadest interpretation so as to encompass all such modificationsand equivalent arrangements.

What is claimed is:
 1. A light-emitting diode, comprising: alight-emitting epitaxial layered unit which includes a firstsemiconductor layer, a second semiconductor layer, and a light-emittinglayer sandwiched between said first and second semiconductor layers, andwhich has a top surface including a first electrode region that includesa pad area and an extension area; an insulation layer disposed on saidfirst semiconductor layer and at said extension area of said firstelectrode region; a transparent conductive layer disposed on said firstsemiconductor layer and covering said insulation layer; a protectivelayer disposed on said transparent conductive layer and having aplurality of first holes formed above and along said extension area ofsaid first electrode region to permit said transparent conductive layerto be exposed; a first electrode which is disposed on said protectivelayer, and which includes a pad portion and an extension portion, saidextension portion filling said first holes so as to electrically connectsaid transparent conductive layer; and a second electrode electricallyconnected to said second semiconductor layer and spaced apart from saidfirst electrode.
 2. The light-emitting diode according to claim 1,wherein each of said insulation layer and said protective layer has athickness which is determined according to an equation of:d=(2k+1)Λ/4n, wherein d is a thickness of each of said insulation layerand said protective layer, k is a natural number of at least 0, Λ is awavelength of light emitted from said light-emitting layer, and n is arefractive index of each of said insulation layer and said protectivelayer.
 3. The light-emitting diode according to claim 1, wherein saidinsulation layer includes a plurality of insulation blocks spaced apartfrom one another.
 4. The light-emitting diode according to claim 3,wherein said insulation blocks of said insulation layer are in positionscorresponding to those of said first holes of said protective layer,respectively, and each of said insulation blocks of said insulationlayer has a cross-sectional area smaller than a size of a correspondingone of said first holes of said protective layer.
 5. The light-emittingdiode according to claim 4, wherein said transparent conductive layercovers said insulation blocks of said insulation layer, and saidtransparent conductive layer and said protective layer definetherebetween a plurality of clearances which are in positionscorresponding to those of said first holes, respectively to permit saidfirst electrode to be filled.
 6. The light-emitting diode according toclaim 3, wherein each of said insulation blocks of said insulation layeris disposed below a corresponding one of said first holes of saidprotective layer, and has a cross-sectional area larger than a size of acorresponding one of said first holes of said protective layer.
 7. Thelight-emitting diode according to claim 3, wherein a proximate one ofsaid insulation blocks relative to said pad area of said first electroderegion have a cross-sectional area larger than that of a distal one ofsaid insulation blocks relative to said pad area of said first electroderegion.
 8. The light-emitting diode according to claim 3, whereinproximate ones of said insulation blocks relative to said pad area ofsaid first electrode region are arranged more densely than distal onesof said insulation blocks relative to said pad area of said firstelectrode region.
 9. The light-emitting diode according to claim 1,wherein a part of said pad portion of said first electrode is in directcontact with a portion of said first semiconductor layer at said padarea of said first electrode region.
 10. The light-emitting diodeaccording to claim 9, wherein said pad area of said first electroderegion includes a central portion, and a part of said pad portion ofsaid first electrode is in direct contact with a portion of said firstsemiconductor layer at said central portion of said pad area of saidfirst electrode region.
 11. The light-emitting diode according to claim10, wherein said insulation layer is further disposed at said pad areaof said first electrode region.
 12. The light-emitting diode accordingto claim 1, wherein said protective layer further has a second holedisposed above said first semiconductor layer at said pad area of saidfirst electrode region.
 13. The light-emitting diode according to claim12, wherein said second hole has an annular geometry.
 14. Thelight-emitting diode according to claim 12, wherein said transparentconductive layer has a third hole disposed above said pad area of saidfirst electrode region, and said first electrode fills said second holeof said protective layer and said third hole of said transparentconductive layer so as to permit said first electrode to be in directcontact with a portion of said first semiconductor layer at said padarea of said first electrode region.
 15. The light-emitting diodeaccording to claim 12, wherein said second hole includes at least onehole-protruding portion that protrudes radially and outwardly.
 16. Thelight-emitting diode according to claim 1, wherein said insulation layeris further disposed on said first semiconductor layer at said pad areaof said first electrode region, said insulation layer at said pad areaof said first electrode region including a plurality of insulationblocks which are arranged to surround a center of said pad area of saidfirst electrode region and which are angularly spaced apart from oneanother.
 17. The light-emitting diode according to claim 16, wherein twoadjacent ones of said insulation blocks at said pad area of said firstelectrode region define therebetween a clearance, and said firstelectrode further includes an interconnecting portion whichinterconnects said pad portion and said extension portion and which isdisposed in a position above a corresponding one of said clearances. 18.The light-emitting diode according to claim 16, wherein said protectivelayer further has a second hole disposed above said first semiconductorlayer at said pad area of said first electrode region, said second holeincluding at least one hole-protruding portion that protrudes radiallyand outwardly.
 19. The light-emitting diode according to claim 18,wherein said second hole includes a plurality of said hole-protrudingportions respectively aligned with said insulation blocks at said padarea of said first electrode region.
 20. The light-emitting diodeaccording to claim 18, wherein said second hole includes a plurality ofsaid hole-protruding portions which are staggered from said insulationblocks disposed at said pad area of said first electrode region.
 21. Thelight-emitting diode according to claim 1, wherein said top surface ofsaid light-emitting epitaxial layered unit further includes a secondelectrode region on which said second electrode is disposed, said secondelectrode region including a mesa portion at which said secondsemiconductor layer is exposed, said protective layer covering said mesaportion and further having a fourth hole to permit a part of said secondsemiconductor layer to expose.
 22. The light-emitting diode according toclaim 21, wherein said insulation layer is further disposed on said padarea of said second electrode region and is sandwiched between saidprotective layer and said second semiconductor layer.
 23. Thelight-emitting diode according to claim 1, wherein said top surface ofsaid light-emitting epitaxial layered unit further includes a secondelectrode region configured as a mesa-shaped surface on which saidsecond electrode is disposed, said second electrode including anextension portion which is disposed on said protective layer and whichextends downwardly to penetrate through said first semiconductor layerand said light-emitting layer to form an ohmic contact with said secondsemiconductor layer.
 24. The light-emitting diode according to claim 23,wherein said insulation layer, said transparent conductive layer, andsaid protective layer are laminated sequentially on said firstsemiconductor layer, and are disposed between said extension portion ofsaid second electrode and said first semiconductor layer.
 25. Thelight-emitting diode according to claim 23, wherein said transparentconductive layer and said protective layer are laminated sequentially onsaid first semiconductor layer, and are disposed between said extensionportion of said second electrode and said first semiconductor layer. 26.The light-emitting diode according to claim 1, wherein said firstelectrode has an undulating top surface.
 27. The light-emitting diodeaccording to claim 1, wherein said pad portion of said first electrodehas a stepped top surface.
 28. The light-emitting diode according toclaim 1, wherein said pad portion of said first electrode has a recessedtop surface.
 29. The light-emitting diode according to claim 28, whereinsaid recessed top surface of said pad portion of said first electrodehas at least two recesses.
 30. The light-emitting diode according toclaim 28, wherein said recessed top surface of said pad portion of saidfirst electrode has a central recess and a surrounding recesssurrounding said central recess.
 31. The light-emitting diode accordingto claim 30, wherein said central recess is deeper than said surroundingrecess.
 32. A light-emitting diode, comprising: a light-emittingepitaxial layered unit which includes a first semiconductor layer, asecond semiconductor layer, and a light-emitting layer sandwichedbetween said first and second semiconductor layers, and which has a topsurface including a first electrode region and a second electrode regionwhich includes a pad area and an extension area, said light-emittingepitaxial layered unit having a plurality of vias, each of which extendsdownwardly from said extension area of said second electrode regionthrough said first semiconductor layer and said light-emitting layer toterminate at a bottom surface in said second semiconductor layer so asto permit said second semiconductor layer to be exposed; an insulationlayer disposed on said pad area and said extension area of said secondelectrode region; a transparent conductive layer disposed on said firstsemiconductor layer and having a plurality of holes which are inpositions corresponding to those of said vias, respectively; aprotective layer disposed on said transparent conductive layer andextending downwardly along an inner peripheral surface of each of saidvias to terminate at said bottom surface of each of said vias to permitsaid second semiconductor layer to be exposed; a first electrodedisposed on said protective layer and at said first electrode region,and electrically connected to said transparent conductive layer; and asecond electrode disposed on said protective layer and at said secondelectrode region, and filling said vias so as to electrically connectsaid second semiconductor layer.
 33. The light-emitting diode accordingto claim 32, wherein said insulation layer is further disposed on saidextension area of said second electrode region, and said transparentconductive layer covers said insulation layer on said extension area ofsaid second electrode region.
 34. The light-emitting diode according toclaim 32, wherein said first electrode includes a pad portion and anextension portion, and said insulation layer, said transparentconductive layer, and said protective layer are laminated sequentiallyon said first semiconductor layer and are disposed between saidextension portion of said first electrode and said first semiconductorlayer.
 35. The light-emitting diode according to claim 32, wherein saidfirst electrode includes a pad portion and an extension portion, saidpad portion of said first electrode being in direct contact with saidfirst semiconductor layer.
 36. The light-emitting diode according toclaim 32, wherein said first electrode includes a pad portion and anextension portion, said pad portion of said first electrode having astepped top surface.
 37. The light-emitting diode according to claim 32,wherein said first electrode includes a pad portion and an extensionportion, said extension portion of said first electrode having a steppedtop surface.
 38. The light-emitting diode according to claim 32, whereinsaid second electrode includes a pad portion and an extension portion,and said protective layer is disposed between said pad portion of saidsecond electrode and said insulation layer.
 39. A method formanufacturing a light-emitting diode, comprising the steps of: a)providing a light-emitting epitaxial layered unit which includes a firstsemiconductor layer, a second semiconductor layer, and a light-emittinglayer sandwiched between the first and second semiconductor layers, thelight-emitting epitaxial layered unit having a top surface including afirst electrode region which includes a pad area and an extension area;b) forming an insulation layer on the extension area of the firstelectrode region of the top surface of the light-emitting epitaxiallayered unit; c) forming a transparent conductive layer on theinsulation layer and the top surface of the light-emitting epitaxiallayered unit; d) forming a protective layer on the transparentconductive layer, the protective layer being formed with a plurality offirst holes above and along the extension area of the first electroderegion to permit the transparent conductive layer to be exposed; and e)forming a first electrode on the protective layer, the first electrodefilling the first holes so as to electrically connect the transparentconductive layer.
 40. The method as claimed in claim 39, wherein in stepa), the light-emitting epitaxial layered unit has a plurality of vias,and the top surface of the light-emitting epitaxial layered unit furtherincludes a second electrode region configured as a mesa-shaped surfacefrom which the second semiconductor layer is exposed partially; in stepd), the protective layer covers the mesa-shaped surface and is formedwith a plurality of openings which are aligned with the vias,respectively so as to permit the second semiconductor layer to beexposed; and in step e), a second electrode is further formed on theprotective layer and fills the vias so as to be in contact with thesecond semiconductor layer.
 41. The method according to claim 39,wherein in step e), the first electrode region is located on the firstsemiconductor layer, and the first electrode is formed directly on thepad area of the first electrode region so as to be in direct contactwith the first semiconductor layer.